The agreement covers 50,000 construction workers on UK projects in oil & gas, petro-chemical and energy projects. It runs from 2013 to 2015.
Unite national officer for construction Bernard McAulay said: "The energy bill is a reminder of the massive contribution construction workers will play in delivering a low carbon energy infrastructure which is fit for purpose.
"The construction industry faces challenging times but after detailed and intense negotiations we have reached a deal which improves pay for construction workers and gives the industry confidence and stability for the next three years."
The agreed pay deal includes 10-day bereavement leave and better terms for redundancy, travel and lodging allowances. The unions and the employers have also agreed to set up a working party to look at improving sick pay.
Unite is signed up to the National Agreement for the Engineering Construction Industry (NAECI) that has operated since 1981. It sets terms and conditions of employment for engineering construction workers.